Just ran 2 chainwhirlers last night main board and I loved it. Went 3-1 for the night losing to Mono U Omni, beating The Gate, R Stompy, and ANT.

Winstigator build

Manabase:
3 Cavern
3 Port
4 Wasteland
1 Pendelhaven
9 Mountain
2 Chrome Mox

I was able to use him to clear some rabblemaster tokens after I was done using them to power my gempalms against stompy.
Attacked into some x/2s with my 1/1s that were snap blocked and then chainwhirler came down to finish them off and leave me with a heavy beater.
Finished off a Jace while also hitting his owner for 1. :D
I never had a huge issue casting him. The one time I didn't have RRR on Turn 3, I didn't want to cast him that turn anyways.
I'm excited to keep using him and I can't wait to see how strong he is against DnT.